suspect it depends on agreements I would use 2NT as a sort of reverse Lebensohl where over partner's 3m bid I could make a NF 3♥ call. I would expect any 3 level call over 2♠ to be forcing What planet do you live on? Without special agreements 2NT is natural, and any 3-level bid is non-forcing. Don't use Muiderberg but was presuming that 2NT was used to find the minor suit in the 2♠ bidders hand. Having seen some your responses at least I am from this universe :)